US10057587B2ActiveUtilityPatentIndex 73

Coding escape pixels for palette mode coding

Assignee: QUALCOMM INCPriority: Jan 31, 2015Filed: Jan 28, 2016Granted: Aug 21, 2018

Est. expiryJan 31, 2035(~8.6 yrs left)· nominal 20-yr term from priority

Inventors:ZOU FENG SEREGIN VADIM KARCZEWICZ MARTA PU WEI JOSHI RAJAN LAXMAN

H04N 19/96H04N 19/61H04N 19/593H04N 19/577H04N 19/52H04N 19/44H04N 19/186H04N 19/176H04N 19/147H04N 19/139H04N 19/13H04N 19/126H04N 19/124H04N 19/105G06F 9/30018

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Claims

Abstract

In one example, a device for decoding video data includes a memory configured to store video data and a video decoder configured to determine that a value for a right shift parameter for an escape-mode coded pixel of a palette-mode coded block of the video data is less than zero, based on the value for the right shift parameter being less than zero, set a value for a left shift parameter to a positive value having an absolute value equal to an absolute value of the right shift parameter, and inverse quantize the escape-mode coded pixel using the value of the left shift parameter.

Claims

exact text as granted — not AI-modified

What is claimed is: 
     
       1. A method of decoding video data, the method comprising:
 obtaining, by a video decoder, an escape-mode coded pixel of a palette-mode coded block of video data, the palette-mode coded block comprising palette index values mapping pixel values for the palette-mode coded block to respective entries of a color palette, the escape-mode coded pixel corresponding to a pixel value that is not in the color palette; and 
 inverse quantizing, by the video decoder, the escape-mode coded pixel using a value of a left shift parameter, wherein inverse quantizing comprises calculating a value for the escape-mode coded pixel (deQuantEspValue) according to a formula comprising:
   deQuantEspValue=EspValue*invQuantScale[qPrem]&lt;&lt;invQuantLeftShift, 
 
 wherein EspValue represents a coded quantized escape value coded for the escape-mode coded pixel, invQuantScale represents an array of inverse quantization scale values, qPrem represents a quantization parameter remainder value, invQuantLeftShift represents the value of the left shift parameter, and &lt;&lt; represents the bitwise left shift operator. 
 
     
     
       2. The method of  claim 1 , further comprising determining the value for the left shift parameter based on a value of a quantization parameter (qP) for the block. 
     
     
       3. The method of  claim 2 , further comprising determining the value of qP based on a color component index (cIdx) of a color component including the escape-mode coded pixel. 
     
     
       4. The method of  claim 2 , wherein determining the value for the left shift parameter comprises:
 calculating a quantization ratio (qPper) according to the formula qPper=qP/6, wherein qP represents the value of the qP; and 
 calculating the value for the left shift parameter using qPper. 
 
     
     
       5. The method of  claim 1 , wherein the array of inverse quantization scale values represented by invQuantScale comprises {40, 45, 51, 57, 64, 72}. 
     
     
       6. The method of  claim 1 , further comprising:
 decoding the color palette for the palette-mode coded block; 
 decoding at least one of the pixel values of the block using the color palette; and 
 reconstructing the block using the escape-mode coded pixel and the decoded at least one of the pixel values. 
 
     
     
       7. A device for decoding video data, the device comprising:
 a memory configured to store video data; and 
 a video decoder configured to:
 obtain an escape-mode coded pixel of a palette-mode coded block of the video data, the palette-mode coded block comprising palette index values mapping pixel values for the palette-mode coded block to respective entries of a color palette, the escape-mode coded pixel corresponding to a pixel value that is not in the color palette; and 
 inverse quantize the escape-mode coded pixel using the value of a left shift parameter, wherein to inverse quantize the escape-mode coded pixel, the video decoder is configured to calculate a value for the escape-mode coded pixel (deQuantEspValue) according to a formula comprising:
   deQuantEspValue=EspValue*invQuantScale[qPrem]&lt;&lt;invQuantLeftShift, 
 
 wherein EspValue represents a coded quantized escape value coded for the escape-mode coded pixel, invQuantScale represents an array of inverse quantization scale values, qPrem represents a quantization parameter remainder value, invQuantLeftShift represents the value of the left shift parameter, and &lt;&lt; represents the bitwise left shift operator. 
 
 
     
     
       8. The device of  claim 7 , wherein the video decoder is further configured to determine the value for the left shift parameter based on a value of a quantization parameter (qP) for the block. 
     
     
       9. The device of  claim 8 , wherein the video decoder is further configured to determine the value of the qP based on a color component index (cIdx) of a color component including the escape-mode coded pixel. 
     
     
       10. The device of  claim 8 , wherein to determine the value for the left shift parameter, the video decoder is configured to:
 calculate a quantization ratio (qPper) according to the formula qPper=qP/6, wherein qP represents the value of the qP; and 
 calculate the value for the left shift parameter using qPper. 
 
     
     
       11. The device of  claim 7 , wherein the array of inverse quantization scale values represented by invQuantScale comprises {40, 45, 51, 57, 64, 72}. 
     
     
       12. The device of  claim 7 , wherein the video decoder is further configured to:
 decode the palette for the palette-mode coded block; 
 decode at least one of the pixel values of the block using the color palette; and 
 reconstruct the block using the escape-mode coded pixel and the decoded at least one of the pixel values. 
 
     
     
       13. The device of  claim 7 , wherein the device comprises at least one of:
 an integrated circuit; 
 a microprocessor; or 
 a wireless communication device. 
 
     
     
       14. A device for decoding video data, the device comprising:
 means for obtaining an escape-mode coded pixel of a palette-mode coded block of video data, the palette-mode coded block comprising palette index values mapping pixel values for the palette-mode coded block to respective entries of a color palette, the escape-mode coded pixel corresponding to a pixel value that is not in the color palette; and 
 means for inverse quantizing the escape-mode coded pixel using the value of the left shift parameter, wherein the means for inverse quantizing comprise means for calculating a value for the escape-mode coded pixel (deQuantEspValue) according to a formula comprising:
   deQuantEspValue=EspValue*invQuantScale[qPrem]&lt;&lt;invQuantLeftShift, 
 
 wherein EspValue represents a coded quantized escape value coded for the escape-mode coded pixel, invQuantScale represents an array of inverse quantization scale values, qPrem represents a quantization parameter remainder value, invQuantLeftShift represents the value of the left shift parameter, and &lt;&lt; represents the bitwise left shift operator. 
 
     
     
       15. The device of  claim 14 , further comprising means for determining the value for the left shift parameter based on a value of a quantization parameter (qP) for the block. 
     
     
       16. The device of  claim 15 , further comprising means for determining the value of the qP based on a color component index (cIdx) of a color component including the escape-mode coded pixel. 
     
     
       17. The device of  claim 15 , wherein the means for determining the value for the left shift parameter comprises:
 means for calculating a quantization ratio (qPper) according to the formula qPper=qP/6, wherein qP represents the value of the qP; and 
 means for calculating the value for the left shift parameter using qPper. 
 
     
     
       18. The device of  claim 14 , wherein the array of inverse quantization scale values represented by invQuantScale comprises {40, 45, 51, 57, 64, 72}. 
     
     
       19. The device of  claim 14 , further comprising:
 means for decoding the color palette for the palette-mode coded block; 
 means for decoding at least one of the pixel values of the block using the color palette; and 
 means for reconstructing the block using the escape-mode coded pixel and the decoded at least one of the pixel values. 
 
     
     
       20. A non-transitory computer-readable storage medium having stored thereon instructions that, when executed, cause a processor of a device for decoding video data to:
 obtain an escape-mode coded pixel of a palette-mode coded block of the video data, the palette-mode coded block comprising palette index values mapping pixel values for the palette-mode coded block to respective entries of a color palette, the escape-mode coded pixel corresponding to a pixel value that is not in the color palette; and 
 inverse quantize the escape-mode coded pixel using the value of the left shift parameter wherein the instructions that cause the processor to inverse quantize comprise instructions that cause the processor to calculate a value for the escape-mode coded pixel (deQuantEspValue) according to a formula comprising:
   deQuantEspValue=EspValue*invQuantScale[qPrem]&lt;&lt;invQuantLeftShift, 
 
 wherein EspValue represents a coded quantized escape value coded for the escape-mode coded pixel, invQuantScale represents an array of inverse quantization scale values, qPrem represents a quantization parameter remainder value, invQuantLeftShift represents the value of the left shift parameter, and &lt;&lt; represents the bitwise left shift operator. 
 
     
     
       21. The non-transitory computer-readable storage medium of  claim 20 , further comprising instructions that cause the processor to determine the value for the left shift parameter based on a value of a quantization parameter (qP) for the block. 
     
     
       22. The non-transitory computer-readable storage medium of  claim 21 , further comprising instructions that cause the processor to determine the value of the qP based on a color component index (cIdx) of a color component including the escape-mode coded pixel. 
     
     
       23. The non-transitory computer-readable storage medium of  claim 21 , wherein the instructions that cause the processor to determine the value for the left shift parameter comprise instructions that cause the processor to:
 calculate a quantization ratio (qPper) according to the formula qPper=qP/6, wherein qP represents the value of the qP; and 
 calculate the value for the left shift parameter using qPper. 
 
     
     
       24. The non-transitory computer-readable storage medium of  claim 20 , wherein the array of inverse quantization scale values represented by invQuantScale comprises {40, 45, 51, 57, 64, 72}. 
     
     
       25. The non-transitory computer-readable storage medium of  claim 20 , further comprising instructions that cause the processor to:
 decode the color palette for the palette-mode coded block; 
 decode at least one of the pixel values of the block using the color palette; and 
 reconstruct the block using the escape-mode coded pixel and the decoded at least one of the pixel values.

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